1. Field of the Invention
The present invention relates to animal insemination, and more particularly to methods and apparatus for inseminating livestock, particularly bovine and related animals.
2. Description of the Prior Art
The artificial insemination of livestock is a common practice, and extensive research and studies have been done to confirm the benefits including increased conception rates. A few devices are currently on the market for use in insemination, especially with respect to the cattle and dairy industry. Most devices currently in use include a syringe of some general design, which contains a unit of semen. The syringe is inserted into the reproductive tract of the animal to deposit the semen in such a location to ensure heightened reproductive success.
The primary goal of and benefit derived from artificial insemination is the ability to select and ensure the delivery of superior genetic traits and to provide improved pregnancy rates. Many factors can affect the pregnancy rate of a herd being artificially inseminated. One factor is the ability to detect when members of the herd are in heat and should be inseminated. Another is the general reproductive health of the female members of the herd. Another factor is the effectiveness of the semen. Another factor is the effectiveness of the artificial insemination procedure being used. Improving the first three factors requires close study of the herd, and testing the reproductive tracts and units of semen being used for any potential problems. A final factor, the effectiveness of the artificial insemination technique, is largely affected by the artificial insemination devices used, and the processes and techniques that are used. With regard to these issues, devices for artificial insemination have been created to be able to quickly and safely deliver semen to a given animal. While a few devices are on the market, there are disadvantages to such devices that either lower their efficiency or make them difficult to use, dissuading a large percentage of technicians from choosing to use them.
Pregnancy efficiency levels are critical since they correlate directly to the cost of breeding livestock. If efficiency is low, more insemination attempts will be needed on average to impregnate a given animal. This translates to a loss of time and profit while the animal is not pregnant, labor costs for the breeder to continue the insemination attempts on the animal, the money cost for more semen to be used, and extra insemination supplies needed for the extra attempts. Thus, an overall increase in efficiency can greatly increase the profitability of a given herd.
One of the more common devices used for the artificial insemination is a gun or syringe having a plunger rod inside that may be enclosed within a sheath. Such a device is disclosed in U.S. Pat. No. 4,493,700. In such a device, a straw containing a unit of semen is placed into the tubular body of the gun, and the sheath placed over the gun-and-straw combination. The contents of the straw may be expelled when the plunger inside the tubular body is depressed. A typical semen straw is sealed at one end by cotton plugs, and at the other end by a crimp seal. When the straw is ready for use, the crimped end of the straw is cut off, opening this end of the straw for passage of the semen. The straw is then inserted into the tubular body of the gun, with the closed end against the plunger, and the open end extending out from the tubular body. Then, the plastic sheath is placed over the tubular body and straw. Both ends of the sheath are open, with the proximal end being of a slightly larger diameter in order to receive the semen straw and tubular body, the distal end having a more narrow frustoconical pointed end or tip. The open split (proximal) end is secured to the gun by means of a locking ring. The tip of the sheath (distal end) is pointed but open to allow for the delivery of semen from the straw. The sheath-covered “loaded” gun is then inserted into the vaginal tract of the animal to be inseminated and, at the proper location, semen is delivered by depressing the plunger. It is to be appreciated that proper insertion and maneuvering of the sheathed gun involves considerable skill as the technician must first direct the pointed end of the sheathed gun assembly through the vaginal canal, then to and through the cervix, and finally to an optimum delivery point at the entrance of the uterine body before the semen is delivered. The slender makeup of such devices makes them well suited for such maneuvering. However, the open-ended sheath suffers from the significant drawback of potential loss of sterility during the long journey to the delivery point, such that even if delivery is made at an optimum location, the semen may have become contaminated along the way rendering it ineffective and/or unusable.
The vaginal canal of most livestock may be unsanitary, the passageway containing bacteria, yeast, and other deleterious organisms. Another problem with bovines is that the vagina is located below the anus, and as such, it is commonplace for some amount of manure to find its way into the vaginal cavity. The manure by nature is unsanitary, and if it is introduced into the cervix or uterus, it will most likely lower reproductive levels to a minimum and cause infection and/or disease. The open-tipped insemination gun may come into contact with and collect these contaminants as it passes through the vaginal cavity, causing them to be deposited with the semen at the delivery point. It is therefore desirable to provide methods and apparatus for artificial insemination that assure sanitary and efficient delivery of the semen to the uterine body.
This problem is partially addressed in U.S. Pat. No. 4,457,313. The devices disclosed in this patent use a disposable rigid protective or outer sheath that fits over the inner sheath of the insemination gun to maintain the sterility of the inner sheath and semen straw inside. The outer protective sheath is formed of a hard plastic and is not as long as the inner sheath. The outer sheath is provided with a perforated rubber cap at one end and a flared gripping surface at the other. The rubber cap prevents contaminants from entering the open end of the pointed sheath and semen straw inside during the long trip through the reproductive tract. When the delivery point is reached, the flared gripping surface is grasped and pulled, sliding the outer sheath relative to the inner sheath (which is why it is shorter than the inner sheath), and causing the inner sheath to push or poke through the perforated rubber cap. The semen can then be delivered by depressing the plunger.
Unfortunately, devices of this sort suffer from numerous drawbacks. The most significant is the obstacle created by the large rubberized cap. While this cap aids sterility, it is bulky and tends to get caught or snag during the trip through the vagina, and is likely to become entangled or stopped (plugged) in the fibrous tissues of the cervix. This makes it difficult for the user to maneuver the tip to the optimum location for deposit of the semen. For smaller animals, the cap may simply be too large to even fit into the cervix. In either case, the rubberized cap prevents the gun from being maneuvered all the way to the uterine body for optimal semen delivery. As a result, at the point where the rubber cap prevents further insertion, the inner sheath must then be pushed through the perforated end of the cap to travel further toward its destination. If the cap has bogged down in the vagina, extending the inner sheath will expose it to the very contaminants sought to be avoided. If the cap has made it to the cervix, further contaminants may still be picked up. In either case, the now bogged-down cap tends to inhibit further maneuvering of the inner sheath (which is passing through it), leading to imprecise positioning and less than optimum deposition of semen. In addition, since the outer protective sheath is of a certain length, even when the user extends the inner sheath the maximum distance through the perforated end of the cap (this distance is the difference between the lengths of the inner and outer sheaths), there is only so much traveling space before the outer sheath rests upon the base of the gun at the plunger, thereby preventing the inner sheath from traveling any further on its own. Oftentimes, this distance is less than the length of the cervix, thereby preventing the tip of the inner sheath from reaching the optimum location at the entrance of the uterine body, decreasing the chances of fertilization.
Another drawback is that the use of the outer sheath increases the size and diameter of the insemination gun, which already includes a first sheath placed over the gun tube, plunger and semen straw. The outer sheath is loosely attached (so that it can slide against the inner sheath), making it more difficult to maneuver. All of these things inhibit the technician from feeling the depth of the insemination gun, contributing to a general lack of ability to feel the placement of the tip of the gun, and making it less likely to deposit the semen in an optimal location.
Because of these problems, many breeders have a difficult time inseminating animals with such devices, and oftentimes choose to use the unsanitary gun or sheath without the protective device. This is usually because the insemination process is based largely on the “feel” the breeder has leading the device through the reproductive tract of the animal, and the sense of location that an experienced breeder acquires though repeated breeding. When breeders discuss “feeling” placement of the artificial insemination gun in the reproductive tract, a central focus is on the travel of the instrument to and though the cervix. The cervix is much more rigid than the vaginal lining, and creates more resistance on the artificial insemination instrument. Depending on the animal and its age, the size, shape, and diameter of the cervix can vary greatly. In general, the cervix in both older and larger livestock is larger and longer than that of younger, smaller livestock. Often times, the angle at which the cervix rests is more downward with an older animal. These differences in cervix size and shape underscore the problems with many of the sanitary devices currently on the market.
Other devices have also been developed to attempt to further sanitize the process. One such device is disclosed in U.S. Pat. No. 4,453,936. This device is a sleeve of thin plastic material such as a film, which covers the gun and inner sheath. The gun is inserted in the reproductive tract of the animal with the film in place over the gun, and once the gun is in the proper location to inseminate the animal, the technician pulls on the film to create a lateral force to tear the film by the pressure on the sleeve at the end of the gun, thereby allowing a passage for the semen from the tip of the inner sheath. Many problems have been encountered with such devices, making them unpopular to breeders and rarely used. While the sleeve is intended to make the insemination process more sanitary, it is found that the sleeve bunches in places during insertion creating pockets where contaminants from the vagina are carried further into the cervix and uterus actually increasing the chance of infection. Another problem with such devices is that the edge of the sleeve where the plastic film is connected tends to cut the vaginal lining, causing bleeding in the animal. This causes general discomfort for the animal and increases the chance for infection. It is also known that blood can kill sperm. Finally, many breeders also complain that the film sleeve affects the “feel” needed to properly inseminate the animal.
It is therefore desirable to provide methods and apparatus for providing sanitary artificial insemination of a wide variety of livestock, while also allowing the breeder to have the necessary tactile sensation for proper placement of the insemination gun for delivery of semen at an optimal location to improve the chances of fertilization.